The structures, known as radomes, provide shelter for the radar stations at the base, which is owned by the Ministry of Defence but operated jointly by British and American intelligence services as a listening station.
Work could be seen taking place at the site this week and one of the golf balls had the appearance of a boiled egg with its top cut off.
An RAF spokesman said: "Routine maintenance is taking place. After years of being subject to the vagaries of the Yorkshire weather, the golf balls start to look a bit tatty. We are currently pursuing a refurbishment programme, replacing the old panels with new, shiny ones. This work is aesthetic, and has no impact on the role or capacity of RAF Menwith Hill."
In 2019, Harrogate Council gave the MOD permission to build three more radomes at the base, which will bring the total number of 'golf balls' to 37.
The radomes protect radars from the weather, while also concealing their operations.
A radome approved in November 2018 was scheduled to be built in August 2021, and the same year the council gave consent for 13 redundant buildings on the site, including an accommodation block, to be demolished.
The number of US personnel based at Menwith Hill has been reduced since 2014 in accordance with changing technological demands.